In the year 2166 humanoid robots were replaced with other types after all humanoid robots were destroyed worldwide in a revolt by humans against the use of robots to do work in place of humans.
Robots that did not look like humans were not as confronting to the millions who had lost their jobs in those countries that had not begun a universal monthly payment to all members of the population.
No job meant no money.
It should have been obvious to the powers that be in the affected countries that having no money and no way to earn any was going to be a problem.
Robots had wheels.
Robots were low to the ground.
Robots understood spoken instructions but did not talk.
Robots were anything but human.
You will have to wait for Maxwell Empire Book 5 to read the account of the revolt.
Until then you can read Maxwell Empire Books 1, 2 and 3.